diff --git a/src/config.rs b/src/config.rs
index 06868bf..43a79a5 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -62,7 +62,7 @@ pub struct Config {
     ///
     /// Filter by image ext
     /// ```
-    /// --preload-regex '(png|gif|jpeg|jpg|webp)$'
+    /// --preload-regex '\.(png|gif|jpeg|jpg|webp)$'
     /// ```
     ///
     /// * requires `storage` argument defined